NEW YORK (CNN) --Huge crowds of anti-war demonstrators jammed into midtown New York on Saturday as protesters in dozens of U.S. cities joined large crowds worldwide in voicing opposition to war with Iraq.

Demonstrators converged near the United Nations to protest the possible war in just one of the more than 600 anti-war rallies around the globe. Organizers estimated the crowd at more than 375,000, but Police Commissioner Ray Kelly estimated turnout at 100,000.

Besides protests in large cities such as Chicago, Illinois; and Los Angeles, California; rallies were held across the United States in smaller towns such as Gainesville, Georgia; Macomb, Illinois; and Juneau, Alaska, according to the anti-war group United for Peace and Justice. (Full story)

In New York on Saturday, a giant puppet depicting President Bush holding buckets of blood and oil towered over the cheering crowd that was pressed against police barricades near U.N. headquarters. The main demonstration stretched 20 blocks down First Avenue, and overflowed onto Second and Third avenues as more people tried to reach the rally.

Nobel Peace Prize winner Archbishop Desmond Tutu and actors Susan Sarandon and Danny Glover were among the speakers at the New York demonstration.

Bundled in a heavy coat and scarf against the freezing cold, Tutu told the cheering crowd, "We are members of one family, God's family, the human family."

"How can we say we want to drop bombs on our sisters and brothers, on our children?" the South African bishop asked.

After leading the crowd to cheer "No!" as a response to "What do we say to war?", Tutu urged Bush to listen.

"President Bush, listen to the voice of the people, for many times the voice of the people is the voice of God," Tutu said. "Listen to the voice of the people saying, 'Give peace a chance.'"

CNN's Maria Hinojosa said the crowd was diverse, with older men and women in fur coats, parents with young children, military veterans and veterans of the anti-war movement.

Adele Welty, whose son, a firefighter, was killed in the attacks of September 11, 2001, said she believed Saddam Hussein was a ruthless dictator but that the United States should work with the United Nations to find a peaceful solution.

"Timothy was at the World Trade Center on September 11 to save lives," she said. "I don't feel that he would sanction innocent lives either in this country or in Iraq being shed in his name."

Although organizers said 312 people were arrested, police said 50 were arrested, and a CNN producer reported seeing police use pepper spray on demonstrators.

Although most protests were peaceful, police arrested 34 in Colorado Springs, Colorado, on failure to disperse and other charges. Police used pepper spray and tear gas to break up the group. After one person threw a tear gas canister back toward the officers, police fired rubber bullets at him and used a stun gun.

In Los Angeles, Director Rob Reiner said those protesting war with Iraq are patriots.

"This is the greatest support we could ever give to our troops because what we are trying to do is protect them from going into harm's way needlessly," Reiner said. "There is no God-awful reason to go to war at this moment. There is no reason to rush into this war, and what we are trying to do is protect our troops from sending them into harm's way."

An 11 year old boy in Los Angeles, a Muslim, said he, too, opposes any war.

"We are here to show our support because we think Bush is doing something wrong," the boy said. "The U.N. inspectors, they didn't get much time, and Bush is just bringing, like, flimsy evidence."

The White House said Saturday that President Bush is still hoping for a peaceful way to disarm Iraqi President Saddam Hussein.

"The president views force as a last resort. He still hopes for a peaceful resolution and that is up to Saddam Hussein," White House spokeswoman Jeanie Mamo said. "The president is a strong advocate for freedom and democracy. And one of the democratic values that we hold dear is the right of people to peacefully assemble and express their views."

Europe sees largest crowds

Three women with sons in the military sing "God Bless America" during a rally in Newton, Kansas, supporting action against Iraq.

Police in London, England, said turnout Saturday was 750,000, the largest demonstration ever in the British capital. The organizers put the figure at 2 million. In Germany, 500,000 protested, and 300,000 gathered in 60 towns and cities across France.

The biggest demonstrations seen in Europe in years were part of marches by millions across the globe, from the Antarctic to Iceland. (Full story)

The demonstrations followed a pivotal day for the United Nations in which a stark division between members of the Security Council was pronounced.

After presentations from top U.N. weapons inspectors, France, Germany, China and Russia suggested giving the inspectors more time, which drew cheers from the chamber. The United States, Britain and Spain said Iraq was not complying with Security Council Resolution 1441, which calls on Iraq to disarm itself of weapons of mass destruction and cooperate with weapons inspectors. (Full story)

Protesters took to the streets in towns and cities across France, and police said that as many as 300,000 are participating in protests in Berlin, Germany.

Protests were peaceful, but violence broke out at a rally in Athens, Greece, when dozens of hooded demonstrators among a large crowd threw rocks and gasoline bombs at police, who responded by firing tear gas.

A police spokesperson blamed the violence on anarchists, who had splintered off from the main group. (Full story)

Tens of thousands demonstrated in Melbourne, Australia, on Friday -- the biggest peace march the city has seen since the Vietnam War -- and on Saturday, tens of thousands of anti-war campaigners flocked to other cities in Australia and New Zealand. (Melbourne's rally)